1. Field of the Invention
The present invention relates to a curtain-type coater for coating paint from above onto a paper web or the like.
2. Discussion of Background Information
The manufacture of coated paper employed for use in catalogues and as heat-sensitive paper and tickets for automated ticketing machines and so on has hitherto involved the coating of a coating liquid onto the surface of a raw material paper web.
Machines used for the coating of coating liquids such as this are referred to as coaters and, of these coaters, those used for the coating of a coating liquid onto a paper web or the like are referred to as curtain-type coaters.
As illustrated in FIG. 6a, in order to coat a coating liquid of a prescribed width onto a web upper surface, a curtain-type coater 100 jets a coating liquid held within a head body 101 in a curtain tc shape from above onto a web surface (not shown in the diagram) being carried in the direction perpendicular to the plane of the paper of FIG. 6a. 
Although different depending on the type of coating liquid t that is used, generally speaking, in the use of the curtain-type coater 100 for the formation of a low flow rate curtain tc of no more than 6 to 7 liters/min/meter width, the edge parts ce of the curtain tc, as illustrated in FIG. 6b, are pulled toward the inner side due to an inner side-directed surface tension which causes instability of the curtain tc of the coating liquid t.
In a curtain-type coater 200 designed to resolve this problem as illustrated in FIG. 7, guide bars gb or guide plates for guiding the curtain tc of the curtain liquid t to prevent the instability thereof are arranged in both ends of a slit (not shown in the diagram) which serves as a jet for the coating liquid t that is held in a head body 201.
It is noted that Japanese Unexamined Patent Application No. 8-1061 discloses a representative example of technology of the prior art pertaining to this application.
By the way, in the use of a general curtain-type coater 100 as described above, when the flow rate of the coating liquid being jetted is low, the edge parts ce of the curtain tc are pulled toward the inner side due to surface tension causing instability of the curtain tc of the coating liquid t.
In addition, if this flow rate is further decreased, a curtain tc of a mottled and raindrop-like spattered state is produced, and maintenance of the prescribed coating performance becomes difficult to achieve.
The resolution of this problem necessitates a flow rate of the coating liquid t of a fixed rate or above which results in the undesirable and unavoidable outcome of excess use of the coating liquid t.
On the other hand, there is a problem inherent to the use of a curtain-type coater 200 in which guide bars gb or guide plates are arranged in that, when the coating operation is continued for long periods, the coating liquid t affixes to the guide bars gb and guide plates and subsequently dries and solidifies which, in the end, disturbs the curtain tc and results in a loss of the guiding function thereof.
In addition, interference between the guide bars gb and guide plates with color pans (not shown in the diagram) for collecting the coating liquid occurs at the initiation of coating and results in an undesirable disturbance of the curtain tc of the coating liquid t.
In addition, the arrangement of guide bars gb and guide plates creates an obstruction to a range of operations including maintenance and, accordingly, reduces the operability of the device.